She was born and raised in Poughkeepsie, New York,[1] and travelled to Palo Alto, California in 1963 with her older brother Don shortly after she was expelled from high school. In early 1964, Garcia met Neal Cassady, who introduced her to Ken Kesey and his friends, one of whom gave her the name "Mountain Girl". Cassady took her to La Honda, California, Kesey's base of operations, where she quickly joined the inner circle of Pranksters and became romantically involved with Kesey, having a daughter by him named Sunshine.[2] The Grateful Dead song "Here Comes Sunshine" may or may not be an allusion to Garcia's and Kesey's daughter – the Dead were fond of lyrics having double, often personal meanings. When Kesey was a fugitive, Garcia had a relationship with another Prankster named George Walker who would become her husband in 1966. The marriage between Garcia and Walker did not last long and they separated in December 1966 and were divorced in 1978. She took up with Jerry Garcia after splitting with Walker, but they did not marry for many years after.

Before marrying Jerry Garcia in 1981, they had two daughters.[1] The family had a house in San Rafael, California as well as a beach house in Stinson Beach, California, but separated after Garcia began a relationship with Deborah Koons. Jerry and Carolyn Garcia divorced in 1994,[1] but remained friends until his death. After the divorce, he married Deborah Koons. He died 18 months later.

After Jerry Garcia's death, Carolyn Garcia was involved in litigation to obtain payments as per their divorce settlement agreement, ultimately agreeing to a $1,250,000 settlement to avoid further legal costs.[3][4]

Garcia wrote a book on marijuana cultivation, called Primo Plant: Growing Sinsemilla Marijuana, first published in 1976 by Bookpeople.[5] Garcia currently sits on the boards of the Rex Foundation and the Furthur Foundation, and is on the advisory board of the Marijuana Policy Project.[6][7] She formerly served on the board of the Women's Visionary Council.[8] Garcia lives near her daughter Annabelle and the Kesey family farm in Pleasant Hill, Oregon.